Detailed Facies Definition and 3D Static Model: Reservoir Management of the Eocene Producing Units in Block X of the Talara Basin in Northwest Peru

Laverde, Fabio (Schlumberger) | Pozo, Gerardo (PETROBRAS Energia Peru) | Miranda de Oliveira, Flavio (PETROBRAS Energia Brazil) | Carrillo, Gonzalo (Schlumberger) | Torres, Kevin Michael (PETROBRAS Energia Peru) | Sanchez, William (Schlumberger) | Alvarez B., Jose Luis (PETROBRAS Energia Peru) | Contreras, Fabio (Schlumberger)


Block X, located in the Talara Basin in northwest Peru, is one of the oldest producing basins in America. The reservoirs that have been studied are the Eocene Mogollon, Ostrea, Echinocyamus, and Helico units. The present structural model has benefited from previous jobs performed by Petrobras, where an old extensive fault system oriented northeast to southwest was affected by a later fault system trending northwest to southeast. Low-angle faults have cut the upper section of the Helico unit, consequently moving older sequences to the northwest. This structural setting controls the distribution of facies bodies, their interaction, size, and geometry, and the quantity of sand facies.

Based on an integrated facies analysis from numerous outcrops, 21 cored wells and more than 750 well-log motifs, a reliable stratigraphic framework was constructed that resulted in the identification of specific facies associations, stratigraphic or depositional surfaces, defining genetic units . Gross depositional fluvio-deltaic environments of the Mogollon succession were interpreted toward the southeast, shoreface at the Ostrea facies throughout the area, the deltaic and fluvial for the Echinocyamus in localized areas, and the tidal flat-beach-coastal plain toward the northeast, with the important development of fan deltas into submarine canyon-fills. This development was recorded within the Helico at the southwest of the study area. Because of the many years of production data available, the geologic model and facies distribution could be adjusted with dynamic data, such as pressure data, production tests and water cut. A possible way of achieving such conditions included adjusting the connectivity between sand bodies, their orientation and the vertical communication.

The products of the integrated study included: 1) mapped areas and zones of potential reservoir connectivity, and 2) geological model building used in 3D geostatic modeling. Mapping of the sequences resulted in the proposal of new infill wells and potential workovers. The results of the 3D static model work were: a) realistic fine-scale geological models that were consistent with the observed data, b) calculations of uncertainties in the oil-in-place volume.